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1 /*
2  * Copyright 2011, The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "MemChunk.h"
18 
19 #include "utils/flush_cpu_cache.h"
20 #include "utils/helper.h"
21 
22 #include <llvm/Support/raw_ostream.h>
23 
24 #include <sys/mman.h>
25 
26 #include <stdlib.h>
27 
28 #ifndef MAP_32BIT
29 #define MAP_32BIT 0
30 // Note: If the <sys/mman.h> does not come with MAP_32BIT, then we
31 // define it as zero, so that it won't manipulate the flags.
32 #endif
33 
34 //#define USE_FIXED_ADDR_MEM_CHUNK 1
35 
36 #if USE_FIXED_ADDR_MEM_CHUNK
37 static uintptr_t StartAddr = 0x7e000000UL;
38 #endif
39 
MemChunk()40 MemChunk::MemChunk() : buf((unsigned char *)MAP_FAILED), buf_size(0) {
41 }
42 
~MemChunk()43 MemChunk::~MemChunk() {
44   if (buf != MAP_FAILED) {
45     munmap(buf, buf_size);
46   }
47 }
48 
allocate(size_t size)49 bool MemChunk::allocate(size_t size) {
50   if (size == 0) {
51     return true;
52   }
53 #if USE_FIXED_ADDR_MEM_CHUNK
54   buf = (unsigned char *)mmap((void *)StartAddr, size,
55                               PROT_READ | PROT_WRITE,
56                               MAP_PRIVATE | MAP_ANON | MAP_32BIT,
57                               -1, 0);
58 #else
59   buf = (unsigned char *)mmap(0, size,
60                               PROT_READ | PROT_WRITE,
61                               MAP_PRIVATE | MAP_ANON | MAP_32BIT,
62                               -1, 0);
63 #endif
64 
65   if (buf == MAP_FAILED) {
66     return false;
67   }
68 
69 #if USE_FIXED_ADDR_MEM_CHUNK
70   StartAddr += (size + 4095) / 4096 * 4096;
71 #endif
72 
73   buf_size = size;
74   return true;
75 }
76 
print() const77 void MemChunk::print() const {
78   if (buf != MAP_FAILED) {
79     dump_hex(buf, buf_size, 0, buf_size);
80   }
81 }
82 
protect(int prot)83 bool MemChunk::protect(int prot) {
84   if (buf_size > 0) {
85     int ret = mprotect((void *)buf, buf_size, prot);
86     if (ret == -1) {
87       llvm::errs() << "Error: Can't mprotect.\n";
88       return false;
89     }
90 
91     if (prot & PROT_EXEC) {
92       FLUSH_CPU_CACHE(buf, buf + buf_size);
93     }
94   }
95 
96   return true;
97 }
98